/* ----------------------------------------------------------------------    
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
*    
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*    
* Project: 	    CMSIS DSP Library    
* Title:		arm_sin_q31.c    
*    
* Description:	Fast sine calculation for Q31 values.   
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the 
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.  

 Modifications 2017  Mostafa Saleh       (Ported to RISC-V PULPino)  
* -------------------------------------------------------------------- */

#include "riscv_math.h"
#include "riscv_common_tables.h"

/**    
 * @ingroup groupFastMath    
 */

 /**    
 * @addtogroup sin    
 * @{    
 */

/**   
 * @brief Fast approximation to the trigonometric sine function for Q31 data.
 * @param[in] x Scaled input value in radians.
 * @return  sin(x).
 *
 * The Q31 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi). */

q31_t riscv_sin_q31(
  q31_t x)
{
  q31_t sinVal;                                  /* Temporary variables for input, output */
  int32_t index;                                 /* Index variables */
  q31_t a, b;                                    /* Four nearest output values */
  q31_t fract;                                   /* Temporary values for fractional values */
  q63_t temp1 = 0x80000000;

  /* Calculate the nearest index */
  index = (uint32_t)x >> FAST_MATH_Q31_SHIFT;
  //printf("index %d\n",index);
  /* Calculation of fractional value */
  fract = (x - (index << FAST_MATH_Q31_SHIFT)) << 9;
  //printf("fract = %X\n",fract);
  /* Read two nearest values of input value from the sin table */
  a = sinTable_q31[index];
  b = sinTable_q31[index+1];
  //printf("a = %X\n",a);
  //printf("b= %X\n",b);
  /* Linear interpolation process */
  sinVal = ((q63_t)(temp1-(q63_t)fract)*(q63_t)a )>> 32;
  //printf("sinVal1= %X\n",sinVal);
  sinVal = (q31_t)((((q63_t)sinVal << 32) + ((q63_t)fract*b)) >> 32);
  //printf("sinVal2= %X\n",sinVal);
  return sinVal << 1;
}

/**    
 * @} end of sin group    
 */
